Elevator belt assembly with noise reducing groove arrangement

ABSTRACT

An elevator load bearing assembly ( 20 ) includes a plurality of cords ( 22 ) within a jacket ( 24 ). The jacket has a plurality of grooves ( 32, 34, 36, 38 40 ) spaced along the length of the belt assembly. Each groove has a plurality of portions ( 50, 52, 54, 56 ) aligned at an oblique angle (A, B) relative to a longitudinal axis ( 48 ) of the belt ( 20 ). In one example, the grooves are separated such that there is no longitudinal overlap between adjacent grooves. In another example, transitions ( 60, 64 ) between the obliquely aligned portions are at different longitudinal positions on the belt. Another example includes a combination of the different longitudinal positions and the non-overlapping groove placement.

BACKGROUND OF THE INVENTION

This invention generally relates to load bearing members for use inelevator systems. More particularly, this invention relates to anelevator belt assembly having a specialized groove arrangement.

Elevator systems typically include a cab and counterweight that movewithin a hoistway to transport passengers or cargo to different landingswithin a building, for example. A load bearing member, such as roping ora belt typically moves over a set of sheaves and supports the load ofthe cab and counterweight. There are a variety of types of load bearingmembers used in elevator systems.

One type of load bearing member is a coated steel belt. Typicalarrangements include a plurality of steel cords extending along thelength of the belt assembly. A jacket is applied over the cords andforms an exterior of the belt assembly. Some jacket applicationprocesses result in grooves being formed in the jacket surface on atleast one side of the belt assembly. Some processes also tend to causedistortions or irregularities in the position of the steel cordsrelative to the exterior of the jacket along the length of the belt.

FIG. 7, for example, illustrates both of these phenomena. As can beseen, the spacing between the exterior of the jacket 200 and the cords210 varies along the length of the belt. As can be appreciated from theillustration, the cords 210 are set within the jacket as if theycomprise a series of cord segments of equal length corresponding to thegroove spacing. FIG. 7 includes an exaggeration of the typical physicalcord layout for purposes of illustration. The actual distortions orchanges in the position of the cords relative to the jacket outersurfaces may not be discernable by the human eye in some examples.

When conventional jacket application processes are used, the manner inwhich the cords are supported during the jacket application processtends to result in such distortion in the geometry or configuration ofthe cords relative to the jacket outer surfaces along the length of thebelt.

While such arrangements have proven useful, there is need forimprovement. One particular difficulty associated with such beltassemblies is that as the belt moves in the elevator system, the groovesand the cord placement in the jacket interact with other systemcomponents such as the sheaves and generate undesirable noise, vibrationor both. For example, as the belt assembly moves at a constant velocity,a steady state frequency of groove contact with the sheaves creates anannoying, audible tone. The repeated pattern of changes in the cordspacing from the jacket outer surfaces is believed to contribute to suchnoise generation.

An alternative arrangement is required to minimize or eliminate theoccurrence of vibrations or an annoying tone during elevator systemoperation. This invention addresses that need.

SUMMARY OF THE INVENTION

In general terms, this invention is a belt assembly for use in anelevator system. The belt assembly includes a plurality of cordsextending generally parallel to a longitudinal axis of the belt. Ajacket over the cords includes a plurality of grooves that areconfigured and spaced to minimize the occurrence of any annoying audiblenoise during elevator operation.

One example belt designed according to this invention includes aplurality of grooves on at least one surface of the jacket. Each groovehas a plurality of portions aligned at an oblique angle relative to thebelt axis. Each groove has a transition between adjacent portions. Eachgroove has a plurality of such transitions and each transition is at adifferent longitudinal position on the belt.

In one example, the different longitudinal positions of the transitionsare achieved by using different oblique angles for different portions ofthe groove. Having the transitions at different longitudinal positionsreduces the noise-generating impact between the belt and sheaves in theelevator system.

Another example belt designed according to this invention includes aplurality of grooves on at least one surface of the jacket. Each groovehas a plurality of portions aligned at an oblique angle relative to thebelt axis. The grooves are spaced apart such that adjacent grooves areon opposite sides of a longitudinal position on the belt.

In one example, adjacent grooves are on opposite sides of an imaginaryline that extends transverse to the belt axis. Such a spacing betweenthe grooves avoids any overlap between any portion of a groove and anadjacent groove. Maintaining such spacing between grooves reduces thenoise-generating energy associated with the impact between the groovesand a sheave as the belt wraps around a portion of the sheave duringelevator system operation.

In one example, the grooves are longitudinally spaced such that spacingsbetween the grooves vary along the length of the belt. Having differentspacings between adjacent grooves eliminates the steady state frequencyof groove contact with other system components, which is a majorcontributor to the potential for undesirable noise or vibration duringelevator operation.

A belt assembly designed according to this invention may include theinventive spacing between grooves, the inventive angular alignment ofgroove segments or a combination of both. The various features andadvantages of this invention will become apparent to those skilled inthe art from the following detailed description of the currentlypreferred embodiments. The drawings that accompany the detaileddescription can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a portion of an example belt assemblydesigned according to an embodiment of this invention.

FIG. 2 is a cross-sectional illustration taken along the lines 2-2 inFIG. 1.

FIG. 3 is a planar, schematic illustration of the groove arrangement ofthe embodiment of FIG. 1 showing selected geometric features.

FIG. 4 is an enlarged view of the encircled portion of FIG. 1, whichschematically illustrates an example groove cross sectionalconfiguration.

FIG. 5 schematically illustrates an alternative groove arrangement.

FIG. 6 schematically illustrates a method of making a belt designedaccording to an embodiment of this invention.

FIG. 7 schematically illustrates a typical cord geometry relative toouter surfaces on a belt jacket according to the prior art.

DETAILED DESCRIPTION

FIGS. 1 and 2 schematically illustrate a belt assembly 20 that isdesigned for use in an elevator system. A plurality of cords 22 arealigned generally parallel to a longitudinal axis of the belt assembly20. In one example, the cords 22 are made of strands of steel wire.

A jacket 24 covers over the cords 22. The jacket 24 preferably comprisesa polyurethane-based material. A variety of such materials arecommercially available and known in the art to be useful for elevatorbelt assemblies. Given this description, those skilled in the art willbe able to select a proper jacket material to suit the needs of theirparticular situation.

The jacket 24 establishes an exterior length, L, width, W, and athickness, t, of the belt assembly 20. In one example, the width W ofthe belt assembly is 60 millimeters, the thickness t is 3 millimetersand the length L is dictated by the particular system where the beltwill be installed. In the same example, the cords 22 have a diameter of1.65 millimeters. In this example, there are twenty-four cords. Thecords 22 preferably extend along the entire length L of the assembly.

The jacket 24 includes a plurality of grooves 30, 32, 34, 36, 38, 40 and42 on at least one side of the jacket 24. In the illustrated example,the grooves extend across the entire width of the belt assembly.

The grooves result from some manufacturing processes, many of which arewell known in the art, that are suitable for forming the belt assembly20. As can best be appreciated from FIG. 2, the grooves extend betweenan exterior surface of the jacket 24 and the surface of the cords 22facing the same exterior surface of the jacket.

Referring to FIGS. 1 and 3, this example embodiment has grooves that aregenerally W-shaped. Each groove includes a plurality of portions thatare aligned at an oblique angle relative to the longitudinal axis 48 ofthe belt. Taking the groove 34 as an example, a first portion 50 extendsat an oblique angle A in a first longitudinal direction. A secondportion 52 extends in an opposite longitudinal direction at the obliqueangle A. A third portion 54 extends in the same direction as the firstportion 50 but at a second oblique angle B. A fourth portion 56 extendsin an opposite longitudinal direction at the second oblique angle B.

In one example, the angle A is approximately 50°. In the same example,the angle B is approximately 53.5°. Utilizing different oblique anglesfor different portions of the groove allows for strategic positioning oftransitions between the obliquely aligned portions.

The groove 34 in FIG. 3, for example, has a first transition 60, asecond transition 62 and a third transition 64. Each transition joinstwo adjacent obliquely angled portions of the groove. Because the firstoblique angle A is different than the second oblique angle B, thelongitudinal position of the transition 60 is different than thelongitudinal position of the transition 64. “Longitudinal position” asused in this description refers to a position on the belt along thelength of the belt (i.e., in a direction parallel to the axis 48).

For example, the distance between the line 70, which extends transverseto the belt axis 48 across the width of the belt, and the transition 60is different than the distance between the line 70 and the transition64. In this example, the transition 60 is closer to the line 70 than thetransition 64 because the angle A is smaller than the angle B. The line70 is provided for discussion purposes and does not indicate a physicalline on the belt.

Keeping the transitions at different longitudinal positions effectivelychanges the phase of the two halves of the groove. Having thetransitions out of phase tends to cancel the energy associated withcontact between the transitions and sheaves. Therefore, the inventivearrangement reduces vibration and noise in an elevator system.

As shown in the illustrated example, the transitions are essentiallypeaks along the groove. In this example, each transition is curvilinear.Having a curved transition between obliquely angled portions of thegrooves that extend in opposite directions reduces the vibration andnoise-generating impact energy associated with the grooves contacting asheave in the elevator system.

As can be appreciated from FIG. 3, in the illustrated example, theportions 50, 52, 54 and 56 are linear over the majority of their length.The linear portions are aligned at the selected oblique angle or angles,depending on the desired groove configuration. This invention is notlimited to a belt having grooves with truly linear portions. In anexample assembly where the portions are at least somewhat curvilinear,tangent lines associated with such a curvilinear portion preferably areat selected oblique angles relative to the belt axis.

In the example of FIG. 3, the spacing 72 between adjacent grooves (i.e.,between the groove 32 and the groove 34, between the groove 34 and thegroove 36 and between the groove 36 and the groove 38, respectively) isselected such that there is no overlap between any portion of anyadjacent groove. Considering the line 70 as indicating a longitudinalposition on the belt 20, the grooves 36 and 38 are on opposite sides ofthe line 70. Accordingly, there is no overlap between any portion of thegroove 36 and any portion of the groove 38. Keeping the entire groove 36longitudinally spaced from the entire groove 38 reduces the vibrationand noise-generating energy associated with the impact between thegrooves and a sheave during elevator system operation.

The spacing 72 between the grooves preferably prevents any overlapbetween adjacent grooves along the entire length of the belt. In someexamples, the spacing 72 may be consistent along the entire length ofthe belt. In other examples, the spacing 72 varies between grooves in aselected pattern as will be described below.

In addition to the different longitudinal positions of the transitionsand the absence of any longitudinal overlap between adjacent grooves, abelt designed according to this invention may include further vibrationand noise reducing features. FIG. 4, for example, shows one embodimentof a groove configuration where the interface between the groove and theexterior surface on the jacket 24 includes a rounded edge or fillet 74.Using such a rounded edge 74 reduces the vibration and noise producingenergy associated with the impact between the groove and a surface on asheave in the elevator system. In this example, the fillets 74 have aradius of curvature that is in a range from about 0.05 to 0.15millimeters.

In the example of FIG. 4, sidewalls 76 of the groove 38 extend from theexterior surface of the jacket 24 to the bottom 78 of the groove, whichis directly adjacent a surface of the cords 22. The intersectionsbetween the sidewalls 76 and the bottom 78 in this example includerounded surfaces having the same radius of curvature as the fillets 74.

In one example, a 0.1 millimeter radius of curvature is used for thefillets 74 and the transitions between the sidewalls and the bottom 78.One example arrangement has the sidewalls 76 arranged at an angle C thatis approximately 30°. An example height of the groove is 0.7 millimetersand an example width S of the groove is 0.7 millimeters.

The configuration of the grooves is dictated in some examples by theshape of the cord supports used during the belt manufacturing process.Those skilled in the art who have the benefit of this description willbe able to select from among commercially available materials used formaking jackets on elevator belts and be able to configure themanufacturing equipment or other groove-forming equipment to achieve thedesired groove profile to meet the needs of their particular situation.

FIG. 5 shows another example belt 20 designed according to thisinvention. In this example, each groove has only two portions 80 and 82extending in opposite longitudinal directions but at the same obliqueangle A. A single transition 84 joins the portions 80 and 82. In thisexample, both portions 80 and 82 extend at the same angle A and thetransition 84 is aligned at the center line 85, which is coincident withthe longitudinal axis of the belt. Of course, other configurations arewithin the scope of this invention.

In this example, the space 86 between adjacent grooves is selected sothat adjacent grooves are on opposite sides of a longitudinal positionon the belt 20. For example, the line 88 indicates a longitudinalposition, which is taken transversely to the axis 85 of the belt. In oneexample, such a line could be drawn between every set of adjacentgrooves and there would be no longitudinal overlap between the groovesbecause each groove would be on an opposite side of such a line.Arranging the grooves to avoid longitudinal overlap reduces the energyassociated with impact between the grooves and the surface of a sheavein an elevator system.

In one example, an embodiment such as that shown in FIG. 5 is used for abelt having a width W that is approximately 30 millimeters while a belthaving a configuration like that shown in FIG. 3 is used for a belt withW of approximately 60 millimeters. The selection of belt width depends,in part, on the expected duty loads for the elevator system in which thebelt will be employed.

FIG. 6 schematically illustrates one example method of making elevatorbelts designed according to this invention. A 60 millimeter wide belt 90having a groove configuration as shown in the embodiment of FIG. 3, forexample, is cut in half along the longitudinal axis of the belt using acutting station 92. Two belts 94 and 96 result, which haveconfigurations as shown in FIG. 5, for example. This strategy for makingelevator belts allows for the same manufacturing equipment to be used toproduce belts having a 60 millimeter wide width and 30 millimeter widewidth, for example.

One example elevator system that includes belts designed according tothis invention includes a plurality of belts in parallel that movesimultaneously over the sheaves. The plurality of belts in this exampleinclude obliquely angled groove portions that are different angles forat least two of the belts. Having different oblique angles on the beltsprovides the benefit of keeping the transitions on one belt at differentlongitudinal positions than the transitions on another belt. Suchlongitudinal positioning effectively changes the phase of at least thetwo belts having different oblique angles. Having the transitions out ofphase allows for the energy associated with contact between thetransitions on one belt and the sheaves to effectively cancel out theenergy associated with such contact between the sheaves and the otherbelt.

In one example, every belt has groove portions angled at a differentoblique angle than the other belts. In another example, the same obliqueangle is used on the belts, however, the belts are aligned relative toeach other in the system such that the groove transitions on one beltare at different longitudinal positions than the groove transitions onat least one other belt.

An additional vibration and noise reducing feature of a belt designedaccording to some example embodiments of this invention includes havingthe grooves spaced apart different distances so that there are differentspacings between various grooves. Referring to FIG. 2, for example, afirst spacing 144 separates the groove 30 from the adjacent groove 32. Adifferent spacing 146 separates the groove 32 from the adjacent groove34. Similarly, at least some of the spacings 148, 150, 152 and 154 varyin size.

It is not necessary that all of the illustrated spacings are different,however, it is preferred to provide at least several different spacingsalong the length of the belt assembly. As a practical matter, a repeatedpattern of the varying spacings will typically extend along the entirelength of the belt assembly 20. Depending on the particulars of the beltassembly and the equipment used to form and apply the jacket 24, thepattern of different spacings will repeat at different intervals.Preferably, the interval of pattern repetition will be as large as themanufacturing equipment allows. In one example, there is a selectedpattern of different spacings that repeats about every fifty grooves orevery two meters of belt length. Within each two meter section, thespacings between adjacent grooves are selected to be varying andnon-periodic.

In one example embodiment, the spacings between the grooves are selectedto be 13.35 millimeters, 12.7 millimeters and 11.8 millimeters. Suchspacings preferably are used in a non-periodic, non-repeating patternover a length of the belt that includes approximately fifty grooves. Inone example, the pattern established by the belt manufacturing equipmentrepeats after every 47^(th) groove. In another example embodiment, thespacings are selected from 11.2 millimeters, 12.1 millimeters and 12.7millimeters. Those skilled in the art who have the benefit of thisdescription will be able to select appropriate groove spacings toachieve the desired level of smoothness and quietness to meet the needsof their particular situation.

In one example, modeling is used to determine the selected spacingdimensions and pattern. The effects of the grooves are characterizedwith a complex waveform to approximate the input disturbance energy. Thecomplex waveform in one example is determined by sampling beltperformance and developing a suitable function that corresponds to thesampled belt behavior. This input function is included for each cord(i.e., each belt segment between adjacent grooves). The summation of thefunctions are based on the relative phase of the cords. The overallenergy is the sum of each cord's contribution. Therefore, the phasing ofthe cords (i.e., spacings between grooves) determines the overallmagnitude. A Fast Fourier analysis provides an assessment of therelative overall energy level resulting from the belt.

By altering spacings between adjacent grooves, the noise component,caused by contact of the belt assembly with other elevator systemcomponents, such as the sheaves, during system operation, is spread overa broader range of frequencies. Thus, steady state frequencies of noiseare avoided which eliminates the potential for an audible, annoyingtone.

In addition to varying the spacing between the grooves, the inventivearrangement provides the ability to vary the lengths of cord “segments,”which result from certain manufacturing techniques (but are notnecessarily included in the inventive arrangement). A belt assemblydesigned according to this invention may include a series of cordsegments along which the distance between the cord and the jacket outersurfaces varies. The ends of such cord “segments” coincide with thelocation of the grooves. Varying the spacing of the grooves also variesthe length of the segments and therefore varies the pattern of the cordgeometry relative to the jacket outer surfaces. With some example usesof the inventive techniques, the length of the cord segments variesalong the length of the belt.

Because the segments of cord extending between adjacent grooves are ofvarious lengths, there is no periodic, repeated geometric pattern of thecords relative to the jacket outer surfaces. By varying the length ofthe cord segments (i.e., changing spacing between similar distortions inthe position of the cord relative to the jacket outer surfaces) anycontribution to noise or vibration caused by the cord geometry, isreduced or eliminated. By eliminating the periodic feature of the cordgeometry, this invention provides a significant advantage for reducingvibration and noise generation during elevator system operation.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this invention. The scope of legal protection given tothis invention can only be determined by studying the following claims.

1-19. (canceled)
 20. An elevator belt for supporting weight associatedwith an elevator car and at least partially wrapping about a sheave thatmoves to cause movement of the elevator car, comprising: a plurality ofcords aligned generally parallel to a longitudinal axis of the belt, thecords being adapted to support the weight associated with the elevatorcar; and a jacket over the cords, the jacket including a plurality ofgrooves on at least one surface of the jacket that is adapted to contactthe sheave, each groove having a plurality of portions at an obliqueangle relative to the belt axis, the grooves being spaced apart suchthat adjacent grooves are on opposite sides of a longitudinal positionon the belt.
 21. The belt of claim 20, wherein the belt has a widthextending in a direction generally perpendicular to the longitudinalaxis between one lateral edge on the belt and an opposite lateral edgeon the belt and wherein each groove extends across the entire width. 22.The belt of claim 20, wherein the longitudinal position extends along aline transverse to the longitudinal axis.
 23. The belt of claim 20,wherein every portion of every groove is on the opposite side of thelongitudinal position from every portion of every adjacent groove. 24.The belt of claim 20, wherein every portion of each groove is at thesame oblique angle.
 25. The belt of claim 20, wherein at least a firstportion is at a first oblique angle and at least a second portion is ata second oblique angle.
 26. The belt of claim 25, wherein each groovehas a transition between the adjacent portions, and wherein at least twoof the transitions are at different longitudinal positions on the belt.27. The belt of claim 25, wherein each groove includes a first portionextending longitudinally at a first oblique angle, a second portionadjacent the first portion extending longitudinally in an oppositedirection at the first oblique angle, a third portion adjacent thesecond portion extending longitudinally in an opposite direction fromthe second portion at a second oblique angle and a fourth portionadjacent the third portion extending longitudinally in an oppositedirection from the third portion at the second oblique angle.
 28. Thebelt of claim 27, including a transition between each of the adjacentportions and wherein each of the transitions is at a differentlongitudinal position from the other transitions.
 29. The belt of claim20, wherein each groove has a transition between adjacent portions andwherein the transitions are curvilinear.
 30. An elevator belt,comprising: a plurality of cords aligned generally parallel to alongitudinal axis of the belt; and a jacket over the cords, the jacketincluding a plurality of grooves on at least one surface of the jacket,each groove having a plurality of portions at an oblique angle relativeto the belt axis with a transition between adjacent portions, eachgroove having a plurality of transitions that are at differentlongitudinal positions on the belt.
 31. The belt of claim 30, wherein atleast a first portion is at a first oblique angle and at least a secondportion is at a second oblique angle.
 32. The belt of claim 31, whereineach groove includes a first portion extending longitudinally at a firstoblique angle, a second portion adjacent the first portion extendinglongitudinally in an opposite direction at the first oblique angle, athird portion adjacent the second portion extending longitudinally in anopposite direction from the second portion at a second oblique angle anda fourth portion adjacent the third portion extending longitudinally inan opposite direction from the third portion at the second obliqueangle.
 33. The belt of claim 30, wherein the transitions arecurvilinear.
 34. The belt of claim 30, wherein the belt has a widthextending in a direction generally perpendicular to the longitudinalaxis between one lateral edge on the belt and an opposite lateral edgeon the belt and wherein each groove extends across the entire width. 35.The belt of claim 30, wherein the grooves are spaced apart such thatadjacent grooves are on opposite sides of a longitudinal position on thebelt.
 36. An elevator system, comprising: a car that is moveable in aselected vertical direction; at least one sheave; and a plurality ofbelts that at least partially wrap around the sheave and move about thesheave as the car moves in the selected direction, each belt having aplurality of cords aligned generally parallel to a longitudinal axis ofthe belt and a jacket over the cords, the jacket including a pluralityof grooves on at least one surface of the jacket, each groove having aplurality of portions at an oblique angle relative to the belt axis,each groove having at least one transition between adjacent portions,the transitions on a first one of the belts being at differentlongitudinal positions than the transitions on a second one of thebelts.
 37. The system of claim 36, wherein the oblique angle of theportions on the first belt is different than the oblique angle on thesecond belt.
 38. The system of claim 37, wherein each groove on thefirst belt includes a first portion extending longitudinally at a firstoblique angle, a second portion adjacent the first portion extendinglongitudinally in an opposite direction at the first oblique angle, andeach groove on the second belt includes a third portion extendinglongitudinally in an opposite direction from the second portion at asecond oblique angle and a fourth portion adjacent the third portionextending longitudinally in an opposite direction from the third portionat the second oblique angle.
 39. The system of claim 36, wherein thetransitions on at least one of the belts are curvilinear.
 40. The systemof claim 36, wherein the grooves on at least one of the belts are spacedapart such that adjacent grooves are on opposite sides of a longitudinalposition between the adjacent grooves.
 41. The belt of claim 40, whereinevery portion of every groove is on the opposite side of thelongitudinal position from every portion of every adjacent groove.